The environment within which a human ambulates--footwear--can have negative effects on the musculoskeletal structures of the body. Examples of these negative effects range from stress/strain syndromes of the lower extremities, including the feet, to chronic reoccurrence of severe headaches. Past efforts to reduce these negative effects have failed to enhance the primary functions of the human foot. These functions are: (1) support, (2) cushioning, and (3) guidance. The failure to address any of these three functions is a primary cause of gait related injury, either impact related or torsional related.
Prior efforts to reduce the negative effects of footwear have failed to address the three primary areas of the foot, which in turn has led to a failure to enhance the three primary functions of the foot. The three primary areas of the foot are the calcaneus, or rear foot region; the midfoot region or tarsus region; and the forefoot or metatarsal head region.
The rear foot region is responsible for cushioning and for stabilization or stability upon heel strike. The midfoot region functions to further enhance cushioning, but more obviously provides stability and guidance. The forefoot region is primarily involved in guidance for push off, and also in cushioning.
It would therefore be useful to provide an innersole/midsole which enhances the three primary roles of the foot by enhancing the functions that occur at the three primary foot regions. In this regard, mention is made of Purslow et al., U.S. Pat. No. 4,908,961 in that "insole" or "innersole" is used in this disclosure with respect to the present invention in conformance with the American usage of the term, which includes lightweight elements which are inserted or lightly attached inside a shoe after construction.
May, U.S. Pat. No. 1,710,936, demonstrates a typical insole/midsole in which attention is paid to only one of the three prime aspects of the foot's function, particularly providing support to the arch of the foot. The failure to deal with the rear foot and forefoot regions of the foot causes May to fail in enhancing the total function of the foot. Specifically, May fails to provide forefoot guidance and rear foot cushioning and stability.
Leighton, U.S. Pat. No. 4,541,184, reveals another trend in footwear innersole/midsole, namely, a focus on cushioning. In Leighton, special material properties are utilized to address the concern of cushioning, particularly in the rear foot and forefoot regions. Leighton, however, neglects to provide features that enhance the other two primary functions of the foot, particularly support and guidance. Similarly, Hones, U.S. Pat. No. 4,932,141 focuses on cushioning in the vicinity of the heel, without any attention to the forefoot and midfoot regions.
Freda, U.S. Pat. No. 2,161,565 relates to an apparatus intended to support the midfoot and forefoot. However, the aspects of guidance and cushioning are not addressed in Freda. Further, the mechanism through which support is provided should also act to brace the foot. Any stabilization of the foot should work in unison with the foot's own mechanism for stabilization and should not provide a device which artificially acts as a crutch for the foot. Becker, U.S. Pat. No. 2,383,583, also focuses on the bracing or the stability aspect of the midfoot. However, there is nothing in Becker that provides any form of enhancement for the primary roles of the forefoot and rear foot.
Sarkozi, U.S. Pat. No. 5,138,774 relates to an innersole system to meet personal support requirements of the wearer. The system, however, does not offer any feature that will enhance cushioning or guidance. Similarly, Phillips, U.S. Pat. No. 4,791,736 is directed to a skiboot orthotic but, the focus of the orthotic is on the arch and not on all three areas of the foot and the functions of those areas. Likewise, Marc, U.S. Pat. No. 5,068,983 and Tilles et al., U.S. Pat. No. 5,146,698 are directed to an insole having a heel piece for improved shock absorption, especially for running shoes, without attention to the midfoot and forefoot regions or, the functions of these regions. And, Schroer, Jr. et al., U.S. Pat. No. 5,282,326 concerns a three quarter length insole to provide arch support without a full consideration of all three regions of the foot or, of the functions of these regions.
Thus, it is evident that the prior art has failed to address all of the regions of the foot or, the functions of these regions. Further examples of such documents, as well as examples of art which teaches away from the present invention by providing hard and soft areas different than those of the present invention are discussed below.
Phillipp, U.S. Pat. No. 5,014,706 relates to an orthotic insole having an outline which is said to resemble that of a foot, with portions of the insole corresponding to the calcaneus, first metatarsal head, fifth metatarsal head, those portions having a first, low hardness, the portion corresponding to the lateral longitudinal arch having a second hardness greater than that of the first hardness, the portion corresponding to the area extending back from the metatarsal arch between the lateral and medial longitudinal arches having a third hardness greater than that of the first and second hardnesses. The area of first hardness can be a cavity. In contrast, in the present invention, a region of high pressure is formed about the periphery of the rearfoot and a lower pressure area is created beneath the calcaneus, an area of high pressure beneath the centroid region of the midfoot (the region defined by the navicular, talus and cuboid) and, a high pressure area about the periphery of the forefoot and an area of lower density or compression beneath the apex of the metatarsal or transverse arch by means of an insole device having a cavity and/or a first lower density or softer material in the lower pressure area beneath the calcaneus, in the lower density or compression area beneath the metatarsal or transverse arch and in the area on either side of the centroid region and, a second higher density or harder material in the other areas. The insole of the present invention is a simpler device which attends to the functions of the regions of the foot by having regions of hardness and softness which differ from those of Phillipp.
Likewise, Meyers, U.S. Pat. No. 4,627,177 provides an insole structure wherein the area under the longitudinal arch and a portion of the medial area of the heel are less compressible or more dense than the remainder of the insole, including the area under the metatarsal or transverse arch, contrary to the present invention. Gardner, U.S. Pat. No. 301,226 relates to an innersole with a soft, flexible material beneath the forefoot and midfoot regions and, a hard material beneath the calcaneus, contrary to the present invention. Edelstein, U.S. Pat. No. 2,909,854 is directed to a pressure relieving insole having an aperture therethrough at a part of the sole bearing a callosity. Edelstein is not concerned with the areas of the foot and their respective functions.
Sullivan, et al., U.S. Pat. Nos. 4,910,886 and 4,694,589 are directed to a shock absorbing insole with low resilience inserts at the heel and at the ball, including to the edges of the ball on each side of the foot, in contrast to the present invention wherein the higher density (harder) material is at the high pressure area about the periphery of the forefoot. Padilla, U.S. Pat. No. 4,955,148 provides a foot support assembly wherein beneath the centroid region there is a recess and, an elevated area in the forefoot and rearfoot regions, directly contrary to the present invention wherein a cavity or recess and/or lower density (softer) material is beneath the calcaneus and the metatarsal or transverse arch and, a harder or higher density material beneath the centroid region.
Glickerson, U.S. Pat. No. 3,233,348 is directed to a laminated insole having flexible top and bottom layers and heel and toe inserts of a stiff or firm material. While the inserts each may have an aperture, contrary to the present invention, the area under the midfoot is formed of relatively soft material (as compared with the inserts). Sawyer, U.S. Pat. No. 492,994 is directed to an inner sole wherein there are openings in the forepart and heelpart with cushioning projecting through the openings, above the upper surface of the marginal portion inner sole at the periphery of the openings (above the dorsal level of the innersole) with a top cover thereover, contrary to the present invention wherein rather than an upwardly projecting cushion, there is a region of softer material and/or a cavity beneath the calcaneus and the metatarsal or transverse arch and, the cavity is on the underside of the innersole. Further, while Sawyer does not limit the number of orifices and upwardly projecting cushions, by identifying the rearfoot and forefoot as places for orifices with upwardly projecting cushions, Sawyer teaches away from the present invention because the present invention includes a relatively hard region or higher density region at the midfoot whereas Sawyer's upwardly projecting rearfoot and forefoot cushions create a void at the midfoot.
Davis, U.S. Pat. No. 4,494,320 and Des. Nos. 267,288 and 267,366 relate to outsoles, not insoles, having a recess at the forefoot and rearfoot. The outsoles of Davis can become filled due to direct contact with the ground and, are not typical outsoles such that shoes therefrom cannot be conventionally resoled. Further, Davis fails to teach or suggest the high and low density materials and regions of the present invention. Additionally, outsoles can have negative impact on the foot; for instance, improper wear of the outsole due to a foot imbalance can only aggravate the problem. Thus, the Davis outsole fails to teach or suggest the present invention or address the issues addressed by the present invention. Famolare, Des. 266,798 is also directed to an outsole, which, while having treads particularly at the forefoot and rearfoot, has a significant heel and, fails to teach or suggest the materials and regions of the present invention.
Mention is also made of: Jalbert et al., U.S. Pat. No. 4,513,518 which relates to an innersole with a layer of polyurethane foam, Shibata, U.S. Pat. No. 5,189,816 which provides a midsole or sole having blades for massaging the sole while walking, Anson, Des. 204,596 directed to an insole having ridges and holes throughout the regions of the foot, Chu, U.S. Pat. No. 5,010,661 which relates to a unidirectional ventilating insole for shoes, Rosen, U.S. Pat. No. 4,931,773 which provides a system for determining the fit of shoes by means of transparent areas in the shoe bottom and, Bradfore, U.S. Pat. No. 363,946 which is directed to a flap connected to the outer surface of the innersole.
Accordingly, it is believed that prior to the present invention an innersole has not been taught or suggested which addresses the three primary functions of the foot (the cushioning, guidance and stability roles of the foot), and which presents features respective to the three primary anatomical regions of the foot, especially by means of two areas of different density.